Your purse or wallet is a key to speedily unlocking £100s of savings. So get it out, and open it up. I'm going to show you how to examine all the main items you keep in there, to check they're the right ones and you're correctly tooled up. If not you can likely save £100s or more.

1.

Pull out your debit card - do you have a winner? The debit card shows where you bank. Here are my key questions...

- Do you pay a monthly fee? If so work out its annual cost (£15/mth = £180) and then ask yourself if the 'extras' they give are worth this. If not, cancel it. Plus if you were flogged it or told you had to have it, you may be able to reclaim all packaged bank fees.

- Are you overdrawn? Debit cards can be debt cards too. For small overdrafts you can switch to First Direct, which gives you £100 which will help clear it, and a £250 0% overdraft. If it's bigger you can use a 0% card to clear your overdraft.
- Does your bank make you happy? If not, again First Direct is worth considering. It gives newbies £100 to switch, and has won every bank service poll we've ever done, with 92% of its customers rating it 'great'. Plus you also get access to a 6% regular savings account.
- Do you have savings? Bank accounts pay the highest interest: Santander 123 pays 3% on up to £20,000; Club Lloyds 4% on £4,000 - £5,000 and TSB 5% on up to £2,000 plus up to £5 a month cashback on contactless purchases.

Switching account these days is quick and easy for most, and can be very lucrative, as Janet emailed: "Been with our old bank for 50 yrs, we were nervous about switching but it all went perfectly, plus we got £100 to spend on holidays. Ta." Full info in Best Bank Accounts.

2.

Got an Oyster card? You may be due a share of £200m+. There's big money sloshing about - if you failed to touch your Oyster out you can often claim back the excess (some have got £70 on this). Plus if you now use your contactless card instead, or if you've an old Oyster, you can claim back old credit. See our Oyster card reclaiming guide for how to do all of them.

3.

Got a credit card(s) that you pay interest on? STOP. Get a 0% balance transfer, that's where it pays off the debt on old cards for you, so you owe the new card, but at 0%. The difficulty is of course getting accepted, so use our Balance Transfer Eligibility Calc to find which top card you've best chances of getting.

Go for the card with the lowest fee, that you're sure you can pay off within the 0% time.

- Longest no-fee 0%:Halifax* is up to 23mths 0% no-fee. - Small fee, longer 0%: Barclaycard* is up to 32mths with a 0.72% fee.
- Longest 0%: If you're unsure, go long: Virgin Money* is 0% for 40mths and the fee is 2.59% (so £25.90 per £1,000 transferred).

Yet never miss repayments and do clear the card before the 0% period ends or they jump to 18.9% rep APR after. Savings can be huge as Victoria tweeted me after using the eligibility calc: "I got my fiancé to transfer his credit card balances to a 0%, saved £1,500 interest." Full help, FAQs & options in Best Balance Transfer Cards.

Got a credit card and always repay in full? Make it PAY YOU. When you use a card, the retailer has to pay the card firm a transaction fee. With a cashback card you effectively get this put in your pocket. As new regulations have cut these fees recently, cashback's been cut too, yet Amex cards are mostly exempted, so still pay a good whack.

The fee-free Amex Everyday* (eligibility calc) pays 5% cashback (max £100) for the first 3mths, then tiered up to 1.25% after. The best non-Amex is Asda Mastercard* which pays 0.5% cashback (1% in Asda). As Anna tweeted me: "@MartinSLewis Glad I read about Amex cashback card: I'll get over £200 paid".

Yet only do this if you'll set up a direct debit to repay IN FULL each month or you'll pay 22.9%/18.9% rep APR interest, which more than wipes the cashback gain. Full options in Top Cashback Credit Cards.

6.

Is it crammed with £100s of coupons? No, why not? You can print 100+ coupons from our coupon page right now, to reduce your weekly shop costs. And to up the gain further, check out Extreme Couponing.

7.

Sign up for a myWaitrose card for FREE daily tea and coffee. Then you can get a free hot drink every day from the machine without buying anything. Or if you spend in their cafe, you get a barista-made cappuccino-type drink for free. See free Waitrose coffee for how.

8.

Not got a credit card... you're less protected & missing free cash. Credit cards have two roles: 1) a way to borrow; 2) a way to spend. If we neutralise the first by setting up a direct debit to repay IN FULL so there's no interest, and you stick within the credit limit, they become much like a debit card, but with two extra benefits...

- Cashback: You get paid to spend, see point 5 above. - Extra protection under 'Section 75 law': Buy something costing £100 to £30,000 on a credit card, and pay for any of it (even 1p) on a credit card, and the card firm's jointly liable with the retailer for the ENTIRE amount. This get-out-of-jail-free card is hugely powerful if the retailer goes bust or won't play fair...

As Michelle tweeted us:"Successful Section 75 credit card claim, refunded £125 for non-delivery of phone order, used template on your website, thanks". See our Section 75 - how to use it guide for full help.

PS: If you've been burnt with credit cards in the past, or have little financial discipline, ignore this point; better safe than sorry.

9.

Is that a condom in the corner? Good. Safety is important. Worth noting though, all condoms have a use-by date. If yours has gone, you can get them free, whatever your age, from clinics and health services. Find your nearest pick-up point: NHS free condom search (in Eng, or see info for Scot, Wales & NI).

10.

Got a gym membership card - when did you last use it? Nowt wrong if you're a regular, but many pay and don't go, as if somehow just having membership makes you fitter. As Jon tweeted me: "Paid £270 for a year's membership, went for one swim. Most expensive swim ever." So be brutal - cancel if you don't go; there are one-off classes and pay-as-you-go gyms, for occasional use. See Cheap Gyms.

11.

Holstering loyalty cards? Max the points. Never choose where you shop on account of a loyalty card, but always have a loyalty card for where you shop regularly. And use them wisely padawans... with a few Jedi tricks you can up the gain. See our points-boosting tricks for Tesco | Nectar | Boots | Morrisons.

12.

Breakdown cover card - don't just renew. When it comes to renewal they often just pump up prices. Yet 88% who try to haggle breakdown prices down with the AA and 85% with the RAC succeed.

Alternatively, use AA/RAC cashback sites to get basic cover from as little as £21. Or AutoAid has full service cover (incl home start & onward travel) for you and your spouse (or civil partner) in any car for £42. Peter emailed us: “The AA renewal fee was £199. With AutoAid it cost £42. Many thanks.”

13.

Got serious wads of cash? It's not always king. I'm not just talking the risk of having your wallet nicked. Cash is less secure as you don't get Section 75 protection (see point 8) as on credit cards, or even the lesser debit card chargeback protection. If you're going to use cash, always keep receipts in case you want to return items.

I remember being contacted by an old gent (in his 90s) who'd paid a big deposit at a restaurant for a planned birthday bash. The restaurant went bust, he asked what he could do. As he paid cash, the answer was nothing. On debit or credit card, there would've been options.

14.

Do you have a donor card? If not, it's worth a thought. It's a big decision, but joining the Organ Donor Register could mean you save or improve up to nine lives. If it's for you, sign up online or call 0300 123 23 23.

15.

Do you have a railcard? Families, couples, students, under-26s - if you ever travel by train, get one. Railcards cost up to £30 a year, but get you a third off most train travel. So they pay for themselves if you spend £90 a year, even just on one trip. And there are far more than you think (eg, the Two Together card for any two people). See Is there a railcard for you?

16.

Do you have a SAD FART wallet? If not, you need it. SAD FART is my way of remembering your consumer rights, and I've a wallet-sized consumer rights guide you can print out and put in there, so if ever you're in dispute, you're armed. Plus St John Ambulance has a pocket-sized first-aid tips guide too.

17.

Do you have an overseas wallet? Savvy travellers have a separate purse or wallet for going overseas. This can seriously save you cash; you can have a look in my overseas wallet here.

Line up everyone with £1,000 of premium bonds in order of their year's winnings, and the person halfway along would have won... not a penny! In fact, you'd need walk past almost two-thirds of the line until you hit the first £25 winner. Premium bonds are the UK's biggest savings product, but their advantages have plummeted. So should you ditch 'em? Martin's done a new statistical analysis of the 14 things every premium bond holder needs to know, here's a lucky dip...

Premium bond prizes are tax-free, but now so are most savings. Since the launch of the personal savings allowance (PSA) on 6 April all savings interest has been paid tax-free, and you only need pay tax if you're a basic 20% rate taxpayer earning over £1,000 interest a year (higher 40% rate £500, additional-rate get no allowance). So premium bonds' tax-free status isn't a biggie for most.

The rate is being cut but you won't win that much anyway. The current prize rate is 1.35%, but it's being cut to 1.25% in June. Yet actually the way it works is: to pay every big prize, lots of people have to earn far less than this prize rate. You can use our unique premium bond win predictor which shows what you're truly likely to win (underneath, to calculate it, it's maths so hard it cuts diamonds). And far more details of how it works in the true premium bond interest rate.

Their big advantage used to be 100% safety. Premium bonds are run by Govt-owned NS&I, so they're 100% safe. But now all UK-regulated savings are protected by the Financial Services Compensation Scheme up to £75,000, and the premium bonds max is £50,000, so the advantage is diminished. See are premium bonds safer?

How does this compare with savings? The top easy-access savings pays 1.45%, save £20,000 and you'll get £290 interest, assuming it's tax-free. Your chances of premium bonds beating it are just 1 in 4. Yet Santander 123 pays 3% at that amount, and the chance of bonds beating that is less than 1 in 40. Full analysis: premium bonds vs savings.

So, should anyone bother with premium bonds? In a nutshell they're best for higher-rate taxpayers who've used up their PSA, ISA allowance and top bank account savings. Though of course this is all based on average luck; and a lucky few always beat the average, so you have to factor that in. For far more read the detailed premium bonds - are they worth it? guide.

It's a year since we introduced the free Resolver tool to MSE - so we're celebrating the successes. Complaining isn't always easy, firms can bluster, ignore or fob off. To level the playing field we married Resolver's tech & our know-how...

How does the tool work? Resolver's* an automated complaints system which helps draft & send letters, monitors replies and escalates it to ombudsmen if needed. It works for nearly 30,000 shops, banks, energy & telecoms firms, public bodies & more. Since we added it to MSE, 270,000 complaints have been filed, and Resolver guesstimates 60% success.

- Flight Delay Compensation. If you've been delayed 3hrs+ any time since 2010 you may be due £200 to £480. Deanne emailed to thank us for Resolver: "We got back £3,300 for our delayed USA BA flight recently. Thanks. So quick and easy." Full help & free tool: Flight Delay Compensation.

- Packaged bank accounts: If you've been persuaded to pay a monthly bank account fee you may be owed £1,000s, as many were mis-sold the added insurance. As Mark tweeted: "Contested mine via Resolver at 6.30am, by midday NatWest had deposited £798 plus interest in my account". And Neil said: "Used MSE & Resolver - got £3,800 for charges since 1996". Full help & free tool: Reclaim Packaged Bank Accounts.
- Experian CreditExpert Reclaiming: We believe it unfairly added insurance between 2011 and 2014. The vast majority of people who try get it back like forumite caz1601: "After reading your article I used your Resolver tool - a couple of days later £245 was in my bank account. Thank you MSE." Full help & free tool: Reclaim CreditExpert.

Of course it can't ensure a win, but it makes the process far easier. Here are a few examples. Melanie tweeted: "@MartinSLewis thanks. Through your site I used Resolver and won against Dune shoes. Faulty boots, no receipt." Louisa emailed: "Full refund of £500 from ExtraEnergy after using Resolver - 8mths of no help until I used it". Brian tweeted: "Many thanks to @MoneySavingExp. Letter from Resolver raised Vodafone's offer of £5 for weeks of stress to £38."

For the full low-down on Resolver incl how it works, how it makes money & its link with MSE, see the Resolver guide.

Look at the numbers. Someone on a standard key or card prepay tariff with typical use pays on average £1,140/yr; switch to the cheapest prepay tariff and it's £1,025/yr (so doing a quick prepay comparison can save you). But the big saving comes from moving to a standard 'billed' meter; the cheapest direct debit tariff is £750/yr. Thankfully last week Npower became the final big 6 firm to stop charges for switching meter. We've updated our Cheap Prepaid guide, in brief...

It might be free, but will they allow you to change to a 'billed' meter? To move off prepayment you'll usually need a) to have paid any outstanding debt you have on your energy account; b) and to be credit scored, so they can see if there's a risk you won't repay. See our full firm-by-firm rules on how to change meter.

I rent, can I switch? You'll need the landlord's permission to change the physical meter (though not to just change tariff). Our renters' energy switch factsheet shows how you can do it and how to persuade your landlord.

Switch meter first, then find the cheapest direct debit deal. For ease, get your current supplier to switch you to a 'billed' meter first, then do a Cheap Energy Club comparison to find your cheapest. If your current provider isn't big 6 (EDF, British Gas, Npower, SSE, Scottish Power & Eon) it may charge you, so switch to a free switching prepay provider first.

Prepay can help you budget. Of course, some find an advantage of prepay is that it helps them budget as they know exactly what they spend. Yet you have to weigh that up against the fact it's so much more costly.

If your supplier/landlord won't let you switch meter, switch prepay tariff and save £100+. It's not as lucrative, though many can save £100+. So do an easy prepay energy comparison. Plus if we can switch you, you can get £30 dual fuel (£15 elec only) cashback too. You're allowed to do this as long as your energy debt isn't £500+.

SUCCESS OF THE WEEK: (Send us yours on this or any topic)"Following your guidance, I've just managed to haggle 35% discount for 9 months' Sky TV (saving c. £200) AND managed to get a free Wi-Fi HD box with free installation thrown in."Check out how to haggle with Sky, the AA and more to save yourself a packet.

What one cuisine could you live off for life? Imagine you're stuck on a desert island for life. There's a food replicator to make you anything you want, BREAKFAST, LUNCH, DINNER & DESSERT, but the setting's stuck on one cuisine. Which would you choose...?

Politicians should show us their tax returns. The majority of people would like all local and national politicians' tax returns to be made public. Just 17 of the 17,574 who voted think only the Prime Minister's tax returns should be made public. On the flipside, 36% of you think it's a private matter. See full results: Should all tax returns be public?

That's it for this week, but before we go, check out this thread from the forum: "Favourite TV Ads, old and new". This week, our forumites are musing over memorable TV ads past and present. Some favourites include the Cadbury bear and 'Be More Dog' from O2. Join in and share your thoughts on which ads warm your soul or grind your gears.

We think it's important you understand the strengths and limitations of this email and the site. We're a journalistic website, and aim to provide the best MoneySaving guides, tips, tools and techniques - but can't promise to be perfect, so do note you use the information at your own risk and we can't accept liability if things go wrong.

What you need to know

This info does not constitute financial advice, always do your own research on top to ensure it's right for your specific circumstances - and remember we focus on rates not service.

We don't as a general policy investigate the solvency of companies mentioned, how likely they are to go bust, but there is a risk any company can struggle and it's rarely made public until it's too late (see the Section 75 guide for protection tips).

We often link to other websites, but can't be responsible for their content.

Always remember anyone can post on the MSE forums, so it can be very different from our opinion.

More about MoneySavingExpert and Martin Lewis

What is MoneySavingExpert.com?Founded in February 2003, it's now the UK's biggest consumer help website with more than 10 million people getting this email and about 13 million using the site every month. In September 2012 it became part of the MoneySupermarket Group PLC. Its focus is simple: saving cash and fighting for financial justice on anything and everything. The site has over 80 full time staff, more than a third of whom are editorial - researching, analysing and writing to continually find ways to save money. More info: See About MSE.

Who is Martin Lewis?Martin set up and runs MSE, and still writes this email each week (unless it says so). He's an ultra-focused money-saving journalist and consumer campaigner with his own ITV prime-time show The Martin Lewis Money Show and weekly slots on Radio 5 Live, This Morning and Good Morning Britain, among others. He's a columnist for publications including the Telegraph, Sunday Mirror and Woman magazine. More info: See Martin Lewis' biography.

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How this site works

We think it's important you understand the strengths and limitations of the site. We're a journalistic website and aim to provide the best MoneySaving guides, tips, tools and techniques, but can't guarantee to be perfect, so do note you use the information at your own risk and we can't accept liability if things go wrong.

This info does not constitute financial advice, always do your own research on top to ensure it's right for your specific circumstances and remember we focus on rates not service.

Do note, while we always aim to give you accurate product info at the point of publication, unfortunately price and terms of products and deals can always be changed by the provider afterwards, so double check first.

We don't as a general policy investigate the solvency of companies mentioned (how likely they are to go bust), but there is a risk any company can struggle and it's rarely made public until it's too late (see the Section 75 guide for protection tips).

We often link to other websites, but we can't be responsible for their content.

Always remember anyone can post on the MSE forums, so it can be very different from our opinion.

MoneySavingExpert.com is part of the MoneySupermarket Group, but is entirely editorially independent. Its stance of putting consumers first is protected and enshrined in the legally-binding MSE Editorial Code.